MR-compatible fluid valve

ABSTRACT

An implantable fluid valve for the adjustable limitation of the fluid pressure in the brain of a patient has all valve component parts composed of non-magnetic material, thereby making the valve MR-compatible.

BACKGROUND OF THE INVENTION RELATED APPLICATION

The present application is a division of U.S. application Ser. No.10/126,045, filed Apr. 9, 2002.

FIELD OF THE INVENTION

The present invention is directed to an implantable fluid valve for theadjustable limitation of the fluid pressure in the brain of a patient.

DESCRIPTION OF THE PRIOR ART

Valves that allow a setting of the maximum pressure from the outside ofa patient, and automatically allow fluid to flow off given excesspressure, are required for patients whose discharge of fluid from thebrain is abnormal.

Valves that can be set from the outside by means of magnetic forces arecommercially available. These valves are not MR-compatible. (As usedherein, MR stands for magnetic resonance.) Examination of the patient inconventional MR scanners thus is not possible without risk, particularlygiven flux densities of 1 T and above. A maladjustment of the programmedpressure level or even damage to the implanted valves is a frequentcomplication even given the use of low-field MR scanners.

Although having parts composed of rubber, a setting of the fluidpressure is not possible at all with a fluid valve disclosed by U.S.Pat. No. 3,595,240, which derives from a time when magnetic resonancesystems were not yet known, so that the problem of an MR-compatiblefluid valve did not arise at all.

In one embodiment of a cerebrospinal fluid shunt valve disclosed in U.S.Pat. No. 4,551,128, adjustment is possible by only puncturing the scalpto allow access of a screwdriver or the like to an adjustment screw.This is unacceptable in practice particularly because of the risk ofinfection and moreover this fluid valve has metallic parts that arefundamentally incompatible with MR. In another embodiment of this knownvalve, magnetic adjustment for the adjustable limitation of the fluidpressure is even worse as to MR compatibility. That embodiment includesmagnetic component parts that could create life-threateningcomplications in conjunction with the extremely high field strengths ofthe basic magnetic field of an MR system. Thus, this known fluid valveis neither suitable for utilization with MR monitoring observation norwas this even envisioned.

The same is also true of a fluid valve according to U.S. Pat. No.5,167,615 that likewise contains magnets for setting the respectivepressure.

British patent application GB 2 143 008 as well as European patentapplication 0 233 325 also disclose valves that are not MR-compatible.The use of stainless steel is expressly prescribed in the former whichmakes this valve non-MR-compatible because MR compatibility not onlyinvolves avoiding magnetic components but also avoiding componentshaving good electrical conductivity since considerable artifacts couldotherwise arise.

SUMMARY OF THE INVENTION

An object of the present invention is to provide an adjustableMR-compatible fluid valve.

This object is inventively in an adjustable valve wherein all valveparts are composed of MR-compatible non-magnetic material. A push-buttonmechanism with key stems that are subcutaneously actuatable through thescalp can be provided for setting the valve parts that can be rotatedrelative to one another.

As a result of the inventive fabrication of all valve components ofnon-magnetic material, for example aluminum, brass, titanium, V4A, steel(CrNiMo steel) plastic or combinations of these materials, a fluid valveis achieved that enables MR examinations of the patient after theimplantation. It has been shown that it is precisely those patients whohave a discharge disorder who require MR examinations of the head withabove-average frequency. The need for MR-compatibility of the fluidvalve is thus intensified. The pushbutton mechanism for the rotaryadjustment of the valve parts relative to one another can be constructedsimilar to the rotary mechanism of ballpoint pens, automatic pencils orthe like wherein a rotary motion is triggered when a button is pressed.Two pushbuttons are preferably provided for the inventive adjustment ofthe setting parts of a fluid valve, one opening the valve step-by-stepand the other pushbutton producing a step-by-step closing of the valve.

In a further embodiment of the invention, an interlock mechanism havingan unlocking element can be provided that must be actuatedsimultaneously with the setting elements. An adjustment of the fluidvalve by actuating the pushbutton mechanism can occur only when theunlocking element, i.e., for example, a further enable button, also ispressed. This prevents an inadvertent adjustment of the pressure settingof this fluid valve when the region of the head of the patient where thefluid valve is implanted under the scalp is inadvertently struck ortouched, which could possibly lead to serious health risks.

Markings that are visible using imaging diagnostic systems can beprovided at the valve parts that are adjustable relative to one another,for example oblong hollow members filled with an MR-visible fluid.Reference markers are also possible that can be seen in X-ray images,ultrasound images or the like.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic section through the implantation location of aninventive fluid valve in the head of a patient.

FIG. 2 is a plan view of the fluid valve in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The illustrated fluid valve 1 is secured to the skull bone 2 under thescalp 3, so that the adjustment pushbuttons 4 and 5 as well as anunlocking pushbutton 6 can be actuated through the scalp 3. Theunlocking pushbutton 6 serves for enabling the adjustment pushbuttons 4and 5. The adjustment pushbuttons 4 and 5 can cause an adjustment of thevalve body parts 7 and 8 that are rotatable relative to one another onlywhen the unlocking pushbutton 6 also is pressed. The pushbuttons 4 and 5respectively serve for opening and for closing the valve. The innervalve part 8 turns one step in the one or other direction relative tothe outer part 7 each time a pushbutton 4 or 5 is pressed. Hoseconnection conduits 9 and 10 allow the inventive fluid valve to beinserted into the fluid system of the patient, so that a discharge ofthe fluid supplied to the fluid valve 1 at 9 ensues via the drain hoseconduit 10.

In order to be able to recognize the setting of the fluid valve from theoutside, reference markers 11 and 12 are attached to the valve parts 7and 8 that are rotatable relative to one another. These referencemarkers can be visual with an imaging diagnostic system, for example anX-ray, ultrasound, or MR system or the like. For recognition in magneticresonance examinations, these reference markers 11 and 12 can be oblonghollow members filled with an MR-visible fluid. For identifying thevalve position, a slice is therefore to be examined such that bothhollow members lie precisely in this slice plane. This is checked in theimage by the length of the image of the hollow member in the slice imagebeing measured. If the measured value is too small, then the measurementlayer has been incorrectly placed. The adjustment of the valve, and thusthe opening pressure, are linearly calculated from the angle of thehollow bodies relative to one another.

Although modifications and changes may be suggested by those skilled inthe art, it is in the intention of the inventors to embody within thepatent warranted hereon all changes and modifications as reasonably andproperly come within the scope of their contribution to the art.

1. An implantable fluid valve comprising: a plurality of valve partsincluding an inlet adapted to receive cerebrospinal fluid and an outletadapted to discharge cerebrospinal fluid and adjustable componentsdisposed in a pathway between said inlet and said outlet for adjustingfluid flow through said pathway; said plurality of valve partscomprising a pushbutton mechanism, separate from said adjustablecomponents, having pushbuttons which interact with said adjustablecomponents to adjust said adjustable components, said pushbuttons beingadapted for subcutaneous actuation by externally applied pressure; andall of said plurality of valve parts being composed of an MR-compatiblematerial.
 2. A fluid valve as claimed in claim 1 wherein said adjustablecomponents include first and second relatively adjustable components,and further comprising reference markers disposed on said relativelyadjustable components which are visible using a diagnostic imagingsystem.
 3. A fluid valve as claimed in claim 2 wherein said referencemarkers comprise hollow members filled with an MR-visible fluid.
 4. Afluid valve as claimed in claim 1 wherein said MR- compatiblenon-magnetic metallic material is selected from the group consisting ofaluminum, brass, titanium CrNiMo steel, and combinations of aluminum,brass, titanium and CrNiMo steel.
 5. A fluid valve as claimed in claim 1wherein said unlocking element is an unlocking pushbutton.